A topping-off ceremony was recently held to celebrate the placement of the last piece of steel on the 86,000-square-foot addition at Genzyme’s Allston Landing biomanufacturing facility along the Charles River in Boston.

The Allston expansion is the latest collaboration between ARC/Architectural Resources Cambridge and Genzyme, a partnership that dates back to 1991 when ARC designed Genzyme’s original Allston facility. Since then, ARC has designed more than one million square feet of new construction and renovation projects for Genzyme, including the brand new 177,000-square-foot Science Center in Framingham.

Over the last few years, Genzyme has expanded production at the Allston facility from four to six bioreactors by fitting-out two cell culture halls, according to a statement from the company.

The current expansion, slated for completion in spring 2010, will allow for the creation of 90 jobs and includes a new, 26,000-square-foot underground cogeneration plant that will generate steam to run the plant’s process operations and will also produce electricity.

Turner Construction Co. is the general contractor for the project.